JP2018130506A - Photoacoustic imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preferably perform imaging on the basis of an acoustic wave generated by light with which a subject is irradiated and an ultrasonic wave reflected by the subject irradiated with the ultrasonic wave.SOLUTION: A photoacoustic imaging device includes a control unit that (a) in a period in which an acoustic wave is detected, controls a switch unit to make the switch unit connect a detection unit with an amplification unit and sets gain of the amplification unit to be first gain; (b) in a period in which an ultrasonic wave is radiated, controls the switch unit to make the switch unit separate the detection unit from the amplification unit and supplies a drive signal for generating the ultrasonic wave to the detection unit as well as sets the gain of the amplification unit to be second gain; and (c) in a period in which a reflection wave is detected, controls the switch unit to make the switch unit connect the detection unit with the amplification unit and sets the gain of the amplification unit to be third gain. In the amplification unit, the second gain is set to be relatively smaller than the first gain and the third gain.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a technique for detecting and imaging an acoustic wave generated by light irradiated on a subject and an ultrasonic wave irradiated and reflected on the subject.

  A conventional example of a photoacoustic imaging apparatus including a detection unit that detects an acoustic wave generated by light applied to a subject and an ultrasonic wave applied to the subject and reflected is disclosed in, for example, Japanese Patent Application Laid-Open No. 2011-229815. (Patent Document 1). In this photoacoustic image generation apparatus, a Q-switch pulse laser is used for the light source unit.

  In order to further reduce the size of the photoacoustic imaging apparatus as described above, it is conceivable to use a light emitting element such as a light emitting diode element instead of the Q switch pulse laser, for example. However, generally, the light intensity of the light emitting element is smaller than that of the Q-switch pulse laser, so that the signal intensity of the acoustic signal is reduced. In this regard, it is conceivable that the acoustic signal is appropriately sized by amplifying the detection signal with an amplifier.

  By the way, considering the case where the function of detecting an acoustic wave and an ultrasonic wave and the function of generating an ultrasonic wave are combined by configuring the detection unit using a piezoelectric element, depending on the configuration of the detection unit, the detection signal may be large. The problem that noise is superimposed may occur. For example, a switch unit is provided between the detection unit and the amplifier, and when generating an ultrasonic wave, a drive signal is supplied to the piezoelectric element of the detection unit with the detection unit and the amplifier disconnected. Thus, when detecting an acoustic wave or an ultrasonic wave, the case where the detection unit and the amplifier are connected and the detection signal from the detection unit is amplified by the amplifier is considered. In this case, when the detector is connected to the amplifier and when the amplifier is disconnected, noise is generated in the switch, and this noise can be superimposed on the detection signal. At this time, if the gain of the amplifier is set to be larger with the use of the light emitting element as described above, since the noise due to the switch unit is also greatly amplified, the detection signal is saturated, and imaging based on the detection signal is performed. There may be inconveniences that cannot be achieved well. On the other hand, when the gain of the amplifier is set to be small, the signal intensity of the detection signal becomes small, and there may be a disadvantage that imaging based on the detection signal cannot be performed well.

JP2011-229815A

  An object of the present invention is to provide a technique capable of satisfactorily imaging based on an acoustic wave generated by light irradiated on a subject and an ultrasonic wave irradiated on the subject and reflected. .

  A photoacoustic imaging apparatus according to one aspect of the present invention includes a light source that irradiates a subject with light, detection of an acoustic wave generated by the light irradiated on the subject by the light source, and ultrasonic waves applied to the subject. A detection unit that selectively executes irradiation and detection of a reflected wave generated by the ultrasonic wave, an amplification unit that amplifies a detection signal of the detection unit, and a switch provided between the detection unit and the amplification unit A control unit that controls each operation of the light source, the amplification unit, and the switch unit, and an imaging unit that generates an image based on the detection signal amplified by the amplification unit, The unit controls (a) the switch unit to connect between the detection unit and the amplification unit in a first period in which the light source is irradiated with the light and the detection unit detects the acoustic wave. And the gain of the amplifying unit is (B) In the second period in which the detection unit is irradiated with the ultrasonic wave, the switch unit is controlled to shut off the detection unit and the amplification unit, and the ultrasonic wave is generated. A driving signal for causing the detection unit to be supplied, and setting the gain of the amplification unit to the second gain. (C) In the third period in which the detection unit detects the reflected wave, the switch unit is The detection unit and the amplification unit are controlled to be connected, and the gain of the amplification unit is set to a third gain. The second gain is more relative to the first gain and the third gain. This is a photoacoustic imaging apparatus that is set to a small size.

  According to the above configuration, since the gain of the amplifying unit is set to be relatively small in a period in which noise due to switching can occur in the switch unit, generation of excessively amplified noise can be suppressed. Therefore, it is possible to satisfactorily perform imaging based on the acoustic wave generated by the light irradiated on the subject and the ultrasonic wave irradiated on the subject and reflected.

FIG. 1 is a block diagram illustrating a configuration of a photoacoustic imaging apparatus according to an embodiment. FIG. 2 is a circuit diagram illustrating a configuration example of the amplifying unit. FIG. 3 is a waveform diagram for explaining the operation of the photoacoustic imaging apparatus.

  FIG. 1 is a block diagram illustrating a configuration of a photoacoustic imaging apparatus according to an embodiment. A photoacoustic imaging apparatus 100 shown in FIG. 1 includes a probe 1, an apparatus main body 2, and a cable 3 that connects them.

  The probe 1 is used by being placed on the surface of a subject P (human body or the like) by an operator, for example, and includes a light source unit 11, a light source drive unit 12, and a detection unit 13. The probe 1 detects the acoustic wave A generated by irradiating the subject P with light and the ultrasonic wave B2 which is the reflected wave generated by irradiating the subject P with the ultrasonic wave B1. It has a function. Detection signals indicating each of the acoustic wave A and the ultrasonic wave B2 detected by the probe 1 are transmitted from the probe 1 to the apparatus main body 2 via the cable 3.

  The light source unit 11 is driven by the light source driving unit 12 to emit light for irradiating the subject P, and includes, for example, a plurality of light emitting elements 11a. The light emitted from the light source unit 11 is, for example, pulsed light having an infrared wavelength (for example, a wavelength of about 850 nm). For example, a light emitting diode element is used as the light emitting element 11a.

  The pulsed light L irradiated to the subject P from the light source unit 11 is absorbed by a detection target (for example, hemoglobin) in the subject P. Then, the detection target object expands and contracts (returns from the expanded size to the original size) according to the irradiation intensity (absorption amount) of the pulsed light, so that the detection target object within the subject P is sounded. Wave A is generated.

  The light source driving unit 12 drives the light source unit 11 based on a light trigger signal provided from the control unit 21 provided in the apparatus main body unit 2. The light source drive unit 12 and the light source unit 11 correspond to the “light source” in the present invention.

  The detection unit 13 generates an ultrasonic wave B1, and detects an ultrasonic wave B2 that is a reflected wave generated when the ultrasonic wave B1 is reflected inside the subject P. For example, a piezoelectric element (ultrasonic vibration) is detected. Child). The detection unit 13 also detects the acoustic wave A described above, and outputs a detection signal obtained when the piezoelectric element vibrates with the acoustic wave A reflected from the subject P.

  Specifically, the detection unit 13 generates an ultrasonic wave B <b> 1 by vibrating the piezoelectric element at a frequency corresponding to the vibrator drive signal given from the control unit 21 of the apparatus main body unit 2. The ultrasonic wave B1 is reflected by a substance having a high acoustic impedance in the subject P to generate an ultrasonic wave B2. The detection unit 13 outputs a detection signal obtained when the piezoelectric element vibrates with the ultrasonic wave B2 reflected from the subject P.

  In the present specification, for convenience of explanation, the ultrasonic wave generated when the detection target in the subject P absorbs light is referred to as “acoustic wave A”, while being generated by the detection unit 13. The ultrasonic wave that is a reflected wave generated by the reflection of the ultrasonic wave B1 in the subject P is distinguished and described as “ultrasonic wave B2”.

  The apparatus main body 2 performs predetermined information processing on the detection signal transmitted from the probe 1 to image it, and displays the imaged acoustic wave A and ultrasonic wave B2. The apparatus main body 2 includes a control unit 21, an amplification unit 22, an imaging unit 23, and an image display unit 24.

  The control unit 21 controls driving of the light source unit 11 by the light source driving unit 12 of the probe 1 and controls operations of the detection unit 13 and the amplification unit 22. The control unit 21 is realized using, for example, a microcomputer that executes a predetermined operation program. Details of each control by the control unit 21 will be described later.

  The amplification unit 22 amplifies the detection signal obtained from the detection unit 13 of the probe 1. The amplifying unit 22 of the present embodiment has an acoustic wave gain that is a gain for amplifying the detection signal by the acoustic wave A and an ultrasonic gain that is a gain for amplifying the detection signal by the ultrasonic wave B2. Etc. can be set variably. A specific configuration example of such an amplification unit 22 will be described later.

  The imaging unit 23 generates an image corresponding to the internal state of the subject P based on the detection signal amplified by the amplification unit 22. Specifically, the imaging unit 23 generates, for example, a tomographic image based on the acoustic wave A or a tomographic image based on the ultrasonic wave B2 using the amplified detection signal.

  The image display unit 24 displays the image generated by the imaging unit 23, and is configured using, for example, a liquid crystal panel.

  As shown in FIG. 1, the imaging unit 23 includes an AD converter (ADC) 31, a reception memory 32, a data processing unit 33, an acoustic image reconstruction unit 34, an ultrasonic image reconstruction unit 35, a detection / A logarithmic converter 36, an acoustic wave image construction unit 37, a detection / logarithmic converter 38, an ultrasonic image construction unit 39, and an image composition unit 40 are included.

  The AD converter 31 converts the detection signal (analog signal) amplified by the amplifier 22 into a digital signal corresponding to the sampling trigger signal from the control unit 21. The detection signal converted into a digital signal by the AD converter 31 is output to the reception memory 32.

  The reception memory 32 is configured to acquire a reception acceptance signal from the control unit 21. When the voltage level of the reception acceptance signal is a predetermined value (for example, high level), the detection signal converted into a digital signal is AD. Obtained from the converter 31 and temporarily stored.

  The data processing unit 33 selectively outputs the detection signal data stored in the reception memory 32 to the acoustic wave image reconstruction unit 34 or the ultrasonic image reconstruction unit 35. Specifically, the data processing unit 33 outputs data based on the detection signal of the acoustic wave A to the acoustic wave image reconstruction unit 34, and outputs the data based on the detection signal of the ultrasonic wave B2 to the ultrasonic image reconstruction unit. 35.

  The acoustic wave image reconstruction unit 34 performs processing for reconstructing data based on the detection signal of the acoustic wave A acquired from the data processing unit 33 as an image. The reconstructed image data is transferred to the detection / logarithmic converter 36.

  The ultrasonic image reconstruction unit 35 performs processing for reconstructing data based on the detection signal of the ultrasonic wave B <b> 2 acquired from the data processing unit 33 as an image. The reconstructed image data is transferred to the detection / logarithmic converter 38.

  The detection / logarithmic converter 36 performs waveform processing on the image data reconstructed based on the detection signal of the acoustic wave A. The waveform-processed data is delivered to the acoustic wave image construction unit 37.

  The detection / logarithmic converter 38 performs waveform processing on the image data reconstructed based on the detection signal of the ultrasonic wave B2. The waveform processed data is transferred to the ultrasonic image construction unit 39.

  The acoustic wave image constructing unit 37 performs processing for constructing a tomographic image in the subject P based on the acoustic wave A based on the data subjected to waveform processing by the detection / logarithmic converter 36. The tomographic image based on the acoustic wave A is delivered to the image composition unit 40.

  The ultrasonic image constructing unit 39 performs processing for constructing a tomographic image in the subject P based on the ultrasonic wave B <b> 2 based on the data subjected to waveform processing by the detection / logarithmic converter 38. The tomographic image based on the ultrasonic wave B <b> 2 is transferred to the image composition unit 40.

  The image synthesis unit 40 performs a process of synthesizing the tomographic image based on the acoustic wave A and the tomographic image based on the ultrasonic wave B2, and outputs a video signal for displaying the synthesized image to the image display unit 24. . That is, both the acoustic wave A and the ultrasonic wave B2 are imaged.

  FIG. 2 is a circuit diagram illustrating a configuration example of the amplifying unit. 2 includes a switch unit 22a, capacitors 22b and 22c, and amplifiers 22d and 22e. As illustrated, the amplification unit 22 has an input end connected to a piezoelectric element as the detection unit 13, and an output end connected to an AD converter 31.

  The switch unit 22 a switches whether to connect between the detection unit 13 and the amplification unit 22 in accordance with a switching signal supplied from the control unit 21. Specifically, when the detection signal obtained by the detection unit 13 is amplified by the amplification unit 22, the switch unit 22 a connects the detection unit 13 to the capacitor 22 b of the amplification unit 22. When supplying the vibrator drive signal from the control unit 21 to the detection unit 13, the switch unit 22 a disconnects the detection unit 13 from the amplification unit 22 and connects it to the control unit 21.

  The capacitor 22b is connected between the switch unit 22a and the amplifier 22d. The capacitor 22b is a coupling capacitor for allowing an AC component to pass through the detection signal input from the detection unit 13 via the switch unit 22a and inputting it to the input terminal of the amplifier 22d.

  The amplifier 22d amplifies and outputs the detection signal input via the capacitor 22b. For example, an operational amplifier can be used as the amplifier 22d.

  The capacitor 22c is connected between the amplifier 22d and the amplifier 22e. The capacitor 22c is a coupling capacitor for passing an AC component without passing through a DC component of the detection signal output from the amplifier 22d and inputting it to the input terminal of the amplifier 22e.

  The amplifier 22e further amplifies and outputs the detection signal input via the capacitor 22c. The detection signal output from the amplifier 22e is input to the AD converter 31. In the present embodiment, an amplifier that can freely increase or decrease the gain at the time of signal amplification under the control of the control unit 21 is used as the amplifier 22e. Specifically, a programmable gain amplifier can be used as the amplifier 22e, for example.

  By controlling the gain in the amplifier 22e by the control unit 21, the gain of the entire amplifier 22d and the amplifier 22e can be variably set. In this embodiment, by setting the gain of the amplifier 22e to be variable, for example, the gain (a gain for ultrasonic waves) when amplifying the detection signal by the ultrasonic wave B2 is about 50 dB, and the detection signal by the acoustic wave A is amplified. The gain (acoustic wave gain) is about 80 dB. That is, the acoustic wave gain is set to be relatively larger than the ultrasonic gain.

  FIG. 3 is a waveform diagram for explaining the operation of the photoacoustic imaging apparatus. The acoustic wave period (first period) prior to time t1 shown in FIG. 3 is a period during which a detection signal from the acoustic wave A is acquired, and an ultrasonic transmission period (second period) between time t1 and time t2. Is a period for transmitting the ultrasonic wave B1, and an ultrasonic wave reception period (third period) after the time point t2 is a period for receiving a detection signal by the ultrasonic wave B2 that is a reflected wave generated by the ultrasonic wave B1. The operation of the photoacoustic imaging apparatus 100 in each period is controlled by the control unit 21 of the apparatus main body 2. Hereinafter, the operation will be described in detail with reference to FIG.

(Acoustic wave period)
The acoustic wave period (first period) is a period during which the light source unit 11 irradiates the subject P with the pulsed light L and causes the detection unit 13 to detect the acoustic wave generated thereby. In this acoustic wave period, the control unit 21 switches the state of the switch unit 22a by supplying a predetermined switching signal (for example, a signal having a relatively low voltage level) to the switch unit 22a of the amplification unit 22, and detects the detection unit. 13 and the amplifying unit 22 are electrically connected. In addition, the control unit 21 supplies a control signal to the programmable gain amplifier 22e of the amplifying unit 22, thereby setting the overall gain of the amplifying unit 22 to an acoustic wave gain (first gain) that is a relatively large value. To do.

  In this state, the control unit 21 supplies a light trigger signal to the light source driving unit 12. Accordingly, the pulsed light L is emitted from the light source unit 11 driven by the light source driving unit 12 to the subject P. The detection unit 13 detects the acoustic wave A generated by the pulsed light L and generates a detection signal thereof. The detection signal transmitted from the detection unit 13 to the amplification unit 22 is amplified by the amplification unit 22 with a relatively large acoustic wave gain and transmitted to the imaging unit 23. The acoustic wave A is imaged by the imaging unit 23 based on the amplified detection signal.

(Ultrasonic transmission period)
The ultrasonic transmission period (second period) is a period during which the detection unit 13 is controlled to irradiate the subject P with the ultrasonic wave B1. In this ultrasonic transmission period, the control unit 21 switches the state of the switch unit 22a by supplying a predetermined switching signal (for example, a signal having a relatively high voltage level) to the switch unit 22a of the amplification unit 22. The section 13 and the amplifying section 22 are blocked, and the detecting section 13 and the control section 13 are electrically connected.

  At this time, as shown in FIG. 3, noise is generated by switching of the switch unit 22a, and this noise is superimposed on the detection signal. For this reason, the control unit 21 supplies a control signal to the programmable gain amplifier 22e of the amplifying unit 22, whereby the overall gain of the amplifying unit 22 is a noise suppression gain (second gain) that is a relatively minimum value. Set to. Thereby, it is possible to prevent the noise from being greatly amplified. The noise suppression gain is preferably set to about 40 dB or less, for example. At this time, the control unit 21 sets the gain of the amplifying unit 22 to the acoustic wave at a time earlier by a predetermined time T1 (for example, 1 μsec), which is a time longer than 0, from the time t1 when the acoustic wave period shifts to the ultrasonic wave transmission period. It is more preferable to change the gain to the noise suppression gain. Thereby, noise amplification can be more reliably suppressed.

  If the noise suppression gain is set to 10 dB or less, noise amplification can be suppressed more effectively.

  In the above state, the control unit 13 supplies a vibrator drive signal to the detection unit 13. Thereby, the piezoelectric element constituting the detection unit 13 vibrates to generate an ultrasonic wave B1, and the ultrasonic wave B1 is irradiated to the subject P.

(Ultrasonic reception period)
The ultrasonic reception period (third period) is a period during which the detection unit 13 detects the ultrasonic wave B2 that is a reflected wave generated by the ultrasonic wave B1. In this ultrasonic wave reception period, the state of the switch unit 22a is switched by supplying a predetermined switching signal (for example, a signal having a relatively low voltage level) to the switch unit 22a of the amplification unit 22, and the detection unit 13 and the amplification unit 22 are electrically connected.

  At this time, as shown in FIG. 3, there is a concern that noise is generated by switching the switch unit 22a, and this noise is superimposed on the detection signal. For this reason, the control unit 21 supplies a control signal to the programmable gain amplifier 22e of the amplification unit 22 to reduce the overall gain of the amplification unit 22 to the above-described noise suppression gain from the ultrasonic transmission period. It is maintained until a predetermined time T2 (for example, 1 μsec), which is a time greater than 0, elapses from the time point t2 when the reception period starts. Thereby, it is possible to prevent the noise from being greatly amplified.

  Since the delay time at the time of gain switching is about 2 μsec, each of the predetermined times T1 and T2 is set to 1 μsec so that the predetermined time T1 + the predetermined time T2 is 2 μsec. The predetermined times T1 and T2 may be set to a time such that the sum is 2 μsec.

  Thereafter, the control unit 21 supplies a control signal to the programmable gain amplifier 22e of the amplifying unit 22, so that the overall gain of the amplifying unit 22 is a value relatively larger than the above-described noise suppression gain. Set to gain (third gain). As illustrated, the ultrasonic gain may be a relatively smaller value than the acoustic wave gain or the same value. In general, an ultrasonic detection signal has a signal intensity (amplitude) larger than that of an acoustic wave detection signal, so that the ultrasonic gain is set to be relatively smaller than the acoustic wave gain.

  In this state, the detection unit 13 detects the ultrasonic wave B2 generated by the ultrasonic wave B1 and generates a detection signal thereof. The detection signal transmitted from the detection unit 13 to the amplification unit 22 is amplified by the amplification unit 22 with an ultrasonic gain. The detection signal transmitted from the detection unit 13 to the amplification unit 22 is amplified by the amplification unit 22 with a relatively large ultrasonic gain and transmitted to the imaging unit 23. Based on this amplified detection signal, the imaging unit 23 images the ultrasound B2.

  According to the embodiment as described above, since the gain of the amplifying unit is set to be relatively small in a period in which noise due to switching can occur in the switch unit, excessively amplified noise is generated and superimposed on the detection signal. This can prevent the detection signal from being saturated. Therefore, it is possible to satisfactorily perform imaging based on the acoustic wave generated by the light irradiated on the subject and the ultrasonic wave irradiated on the subject and reflected.

  Note that the present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, in the above-described embodiment, the switch unit is provided inside the amplification unit, but the switch unit may be provided outside the amplification unit.

  Further, in the above-described embodiment, the amplifier 22 is operated from a time point that is earlier than the time point t1 that is the start of the ultrasonic transmission period by a predetermined time period T1 to a time point that is later than the time point t2 that is the last time of the ultrasonic wave transmission period by a predetermined time period T2. Although the gain is reduced to the noise suppression gain, in principle, it is sufficient to reduce the gain of the amplifier 22 to the noise suppression gain at least in the same period as the ultrasonic transmission period.

  In the above-described embodiment, the programmable gain amplifier is used to variably set the gain of the amplifier 22, but other means may be used. For example, the gain can be variably set by preparing a plurality of stages of amplifiers in the amplifier 22 and selectively connecting amplifiers of any number of stages by using a switch unit or the like.

  In the above embodiment, the wavelength of light emitted from the light source is in the infrared region (for example, 850 nm), but the wavelength is not limited to this. Furthermore, although the light emitting diode element was illustrated as a light emitting element which comprises a light source, it replaces with this, for example, an organic light emitting diode element may be used and a semiconductor laser element may be used. However, it is preferable to use a light-emitting diode element because a photoacoustic imaging apparatus can be configured at a particularly low cost.

  The specific configuration example described in the embodiment is merely an example, and another configuration having the same function as that of the embodiment may be employed. For example, the control unit 21 may use a PC (Personal Computer) instead of a microcomputer.

DESCRIPTION OF SYMBOLS 1 ... Probe 2 ... Apparatus main-body part 3 ... Cable 11 ... Light source part 11a ... Light emitting element 12 ... Light source drive part 13 ... Detection part 21 ... Control part 22 ... Amplification part 22a ... Switch part 23 ... Imaging part 24 ... Image display part 100: Photoacoustic imaging apparatus P: Subject

Claims (6)

A light source for irradiating the subject with light;
A detection unit that selectively executes detection of acoustic waves generated by the light applied to the subject by the light source, irradiation of ultrasonic waves to the subject, and detection of reflected waves generated by the ultrasonic waves;
An amplifier for amplifying the detection signal of the detector;
A switch unit provided between the detection unit and the amplification unit;
A control unit that controls each operation of the light source, the amplification unit, and the switch unit;
An imaging unit for generating an image based on the detection signal after being amplified by the amplification unit;
Including
The controller is
(A) In a first period in which the light source is irradiated with the light and the detection unit detects the acoustic wave, the switch unit is controlled to connect between the detection unit and the amplification unit, and Set the gain of the amplifier to the first gain,
(B) In the second period in which the detection unit is irradiated with the ultrasonic waves, the switch unit is controlled to block between the detection unit and the amplification unit and to generate the ultrasonic waves And a gain of the amplifying unit is set to a second gain,
(C) In a third period in which the detection unit detects the reflected wave, the switch unit is controlled to connect the detection unit and the amplification unit, and the gain of the amplification unit is set to the third gain. Set
The second gain is set to be relatively smaller than the first gain and the third gain.
Photoacoustic imaging device. The control unit maintains the gain of the amplifying unit as the second gain until a predetermined time elapses from the time when the second period is shifted to the third period.
The photoacoustic imaging apparatus according to claim 1. The control unit sets the gain of the amplifying unit to the second gain at a time earlier by a predetermined time than the time of transition from the first period to the second period;
The photoacoustic imaging apparatus of Claim 1 or 2. The third gain is set smaller than the first gain;
The photoacoustic imaging apparatus of any one of Claims 1-3. The amplifying unit includes a programmable gain amplifier,
The control unit sets the overall gain of the amplification unit to any of the first gain, the second gain, or the third gain by controlling the gain of the programmable gain amplifier.
The photoacoustic imaging apparatus of any one of Claims 1-4. The light source includes one or more light emitting elements,
The light emitting element is a light emitting diode element, an organic light emitting diode element or a semiconductor laser element.
The photoacoustic imaging apparatus of any one of Claims 1-5.

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